It appears this was related to CSS variable support. Typora's themes use CSS3 variables which aren't supported in IE and weren't supported in Edge until more r

It appears this was related to CSS variable support. Typora's themes use CSS3 variables which aren't supported in IE and weren't supported in Edge until more recently. I tried on Edge 42 (EdgeHTML 17) when I said the background colour displayed correctly. Perhaps you're using an older version of Edge (the version is displayed at the bottom of the settings panel). In any case, I've added CSS to set the background colour without using CSS variables. It now shows correctly for me in IE 11 too. Thanks for letting us know.